1. Technical Field
The present invention relates to surgical instruments. In particular, instruments used for the extracorporeal application of non-locking and locking slip knots to endoscopic suture and loop ligatures.
2. Background Art
A wide variety of endoscopic surgical techniques for securing tissue has been developed. In addition to the suture and loop ligature methods which are the subject matter of this invention, alternative techniques to the suture and/or ligature method include the use of mechanical devices such as staples, silastic rings and clips, automatic stapling devices, electrosurgery and lasers. A high proportion of endoscopic surgeons experience difficulty in acquiring and maintaining proficiency in their use. These alternate techniques are costlier and may be associated with technical problems, more extensive tissue damage and other surgical complications.
While great advances have been made to improve them over time, improvements in endoscopic suture and loop ligatures are highly desirable because this is the preferred technique in open surgery, which is the standard for operative laparoscopy. Surgeons have mastered the suture method in open surgery and have trusted it over many years to be the most reliable and cost effective technique.
The suture method is superior at repairing organs after portions have been excised from them. For instance, as in a myomectomy procedure, the uterus can be restored. Further, in tubal reconstructive surgery, the patency of the fallopian tube can be best restored with suturing techniques. Procedures to elevate the bladder and correct urinary incontinence are likewise best done with the suture method.
Suturing is a superior technique to effect hemostasis, particularly of large blood vessels. It provides precision in handling the tissues, which is often required when operating in areas where the bowel, ureter, or other structures may be dangerously close to the operative site, particularly in cases where the anatomy has been distorted by adhesions, tumors, endometriosis, or inflammation.
Automatic gun staplers are too wide and rigid in shape, and may lack the precision that is required on the aforementioned surgical conditions.
In this regard, the problem with electrosurgery is the so called "field effect" that is produced by the spread of heat, which destroys a wider sector of tissues around the target. When used to effect hemostasis of large vessels, electrosurgery frequently causes extensive tissue damage.
Another example of the more extensive tissue damage of electrosurgery as compared to sutures is in tubal ligation. For electrosurgery to be effective and reliable, the surgeon must completely coagulate at least three centimeters of the tube. With the suture method, only one centimeter of the tube is taken out, which is advantageous in the event that the patient requires a tubal reanastomosis to be performed in the future. An additional advantage is that a specimen is obtained that can be examined histologically.
Silastic rings may slip off the fallopian tube, producing a failed tubal ligation.
Securing surgical ties is standard practice in open laparotomy surgery. In this form of surgery, the surgeon has wide and direct access to the operative site and can secure surgical ties with relative ease. As a result, the surgeon in this type of operative environment has great flexibility in how ligatures are applied and secured.
While this provides advantages to both the surgeon and patient, there are also serious drawbacks to this type of surgery. In particular, the size of the incision required to effect access by the surgeon creates scarring which may be of significant concern to the patient. In addition, larger incisions create larger areas which not only are injured by the incision and require greater effort to heal, but also create more potential areas of infection, more post operatory pain, and more respiratory, urinary, and gastrointestinal difficulties that may prolong the convalescence period.
One solution to these problems has been provided by the development of laparoendoscopic surgery. In this type of surgery, an illuminated tubular instrument, a laparoscope, is passed through a puncture wound in the abdomen. The laparoscope typically is used not only for examinations, but also for a variety of surgical procedures (e.g., tubal ligations, removal of tumors of the ovaries or uterus, etc.). One of the principle advantages of a laparoscope is the reduced size of the incision required to effect the surgery. Further, depending on the surgical procedure being performed, residual scarring may effectively be reduced, as well as post operatory complications. The foregoing advantages mean that hospital stays may be reduced and/or eliminated, making outpatient ambulatory surgery possible. The cost of surgery may be therefore lower and full recovery faster.
While prior approaches to laparoscopic surgery have produced the aforementioned benefits to patients, they have had an adverse effect on the surgeons flexibility in adequately applying available suturing techniques for a given situation. In particular, the limited use of the suture method in laparoendoscopic surgery is due to the difficulties that surgeons currently encounter in locking their ties. The Surgeon's Knot and/or hitch knots are well known in the art and are the type of knots most frequently used in operative laparoscopy, but these knots have a tendency to loosen up before a second throw can be made, which may render the tie ineffective. In comparison, slip knots have better slipping strength. Non-locking slip knots have less slippage power than self locking slip knots. This difference in slippage power increases after the noose is tied proportionally to the force applied on the standing part suture that closes it.
Prior art ligator devices have been developed which use slip knots. The slip knots currently in use in commercially available loop ligature and suture ligature kits are the Roeder loop, and the Duncan loop. Both of these knot types are well known in the art. The problem with using the Roeder loop, and to a lesser degree the Duncan loop, is that they are not effectively locked and the tie needs to be secured with an additional knot.
Another problem associated with the design used for these slip knots is that the manufacturers typically trim the end suture strand too short (i.e., very close to the knot). As a result, the noose of the slip knots can be tightened but not the knot itself. For this reason, the surgeon cannot restore the loss of slippage power of the knot that occurs when the noose is applied on the tissues. In addition, the slip knots cannot be effectively locked without pulling the end portion of the suture against the knot. Therefore, the prior art Roeder and Duncan loops whose end portions are trimmed will remain unlocked on the tissues.
An example of this slippage is shown in study by Hay et al (Hay D L, Levine R L, von Fraunhofer J A, Masterson B J. Chromic gut pelviscopic loop ligature: Effect of the number of pulls on the tensile strength. J Reprod Med 1990, 35:260-2) (hereinafter, Hay). In this study, it was demonstrated under laboratory conditions that with a commonly known knot called the Roeder loop, the least slippages occurred when only one pull was used to apply the loop ligature. In the study, two out of five loop ligatures had slippage with one pull. However, the slippage rate increased with each additional pull to three out of five; and to four out of five loop ligatures tested.
This problem is more apparent when newer materials, such as polyglactin (Vicryl Dexon), polydioxanone (PDS) or poliglecaprone (Monocryl) are used. These suture materials have comparatively less slippage power than catgut. However, catgut is a highly reactive material which is being replaced. The advantage of the newer materials is that they cause less foreign body inflammatory reaction and may be potentially better than catgut, provided that the suture or loop ligature is properly secured.
In addition to the problem discussed above (i.e., the inability of prior art knots to tighten the knot itself, and then lock the knot due to the excessively trimmed end portion of the suture), the excessively short end suture strand also precludes locking the slip knot with an additional security knot. To compensate for this potential problem, Hunt advises using three loop ligatures to tie pedicles such as a fallopian tube (Hunt R. Atlas of Female Infertility Surgery, Second Edition, 1992 Mosby Year Book. Page 264-267). These multiple ligatures are not locked. Of course, each ligature increases the devascularization of tissue and inflicts some tissue damage when applied. This brings about an increase of inflammation secondary to the resorption of devitalized tissue that must be eliminated and a foreign body inflammatory reaction to the excess suture material, with the possibility of adhesions and of secondary intestinal obstruction. Therefore, the application of three ligatures may result in some additional damage to the ligated tissue and other intraperitoneal organs.
Surgeons would prefer to avoid using multiple ligatures as long as they can rely on the fewer ligatures remaining securely tied. If a single tie is properly locked, as in open surgery, the surgeons seldom feel the necessity to add multiple ligatures on a single pedicle. Unless ligature manufacturers stop trimming the end of the suture, surgeons need to make their own suture and loop ligatures, leaving enough length of end suture to add a security knot using either an intracorporeal or extracorporeal tying technique. Intracorporeal tying techniques are difficult to master to a degree comparable to open surgery, and can be quite time consuming to perform. Making the knot intracorporeally, and tying it with the appropriate tension is more difficult and time consuming to the surgeon which in turn creates higher cost to the patient. Further, the reduced efficiency of the surgeon and the increase in time taken to complete the surgery means that the patient is exposed for a longer period of time to the stress of surgery and anesthesia and increases the cost of surgery. This may in turn negate the benefits of laparoscopic surgery and create a logistical problem for busy surgical facilities and personnel in terms of manpower efficiency which also increases patient costs.
Therefore, this intracorporeal knot technique, while addressing some of the problems caused by slippage, has drawbacks which create both economic inefficiencies and health risk, both of which will ultimately be borne by the patient. Extracorporeal knot tying is more efficient and easier for the surgeon to master. By enabling the surgeon to more quickly complete the surgery, the patient is spared the aforementioned potential problems of intracorporeal knot tying.
The prior art has not recognized that leaving both suture strands sufficiently long to span the distance from the target tissues to the outside makes it possible to extracorporeally tighten slip knots and restore the slippage power; and to lock a self locking slip knot. In addition, it provides the endoscopic surgeon the ability to secure the loop ligature with extracorporeal knots, as in open surgery, avoiding the necessity of using multiple ligatures on a single pedicle.
The use of slip knot for suture ligatures has the additional problem of the "sawing effect" in which the suture that is passed through the tissues slides against the tissues and damages them much like a rope can damage the skin of the hands holding it. Those skilled in the art will recognize that the sawing effect only applies to suture ligatures. In a loop ligature, the suture material surrounds the tissue and, therefore, will not saw through it. One known technique that takes advantage of the superior holding power of a slip knot and can decrease the sawing effect that a slip knot may produce upon initial tightening is to first pass the suture needle that is attached at the end of one of the suture strands of the slip knot, first through the tissues that are being suture ligated, and then through the noose of the slip knot that has been introduced into the peritoneal cavity together with the suture needle. In this needle-thru-noose technique, the suture needle may be placed on the suture strand that controls the closure of the noose, which is called the "standing part" or similarly, the suture needle may be placed on the other suture strand, which is called the "end portion". These two approaches are useful, but limited because their ties remain unlocked. In addition, the ready made suture kits using these two approaches have a limited availability of suture materials and needle sizes.
The same can be said of the pretied suture method that is commercially available as the "Pretied Endoknot Suture" from Ethicon, Inc., which consists of a suture needle that is attached to the standing part and is passed first through the tissue and then through the noose of a wire guide which is then pulled back passing the standing part into the lumen of the tubular ligator and out through the proximal opening of the tubular ligator. The loops of the knot, that are pretied around the shaft of the tubular ligator are then advanced over its distal end to form a knot. This pretied method of the prior art can save time and avoid errors when fashioning the knots. However, since the knot is completed extracorporeally and then reintroduced, the large noose that extends from the knot to the target tissues requires more suture material to pass under tension through the tissues. This represents no advantage in terms of the sawing effect on tissues upon initial tightening of the slip knot when compared to prior art methods of fashioning and/or delivering an extracorporeal slip knot.
Thus, the drawback to the Pretied Endoknot Suture technique is that the knot must be completed outside the peritoneal cavity and then reintroduced. The large resulting noose extends from the outside to the target tissues which therefore requires more suture material to pass through the tissues, under tension, producing the so called "sawing effect." The large size of the noose creates more trauma to the tissue as more suture material is passed through it to close the noose as compared to the small size noose of an intracorporeal knot.
While the prior art has addressed many of the problems associated with ligature application, it has failed to provide surgeons the ability to effectively use the full spectrum of suture knots without adverse side effects, such as the "sawing effect" or tie slippage problems discussed above. In particular, the prior art has not provided the means to most effectively and efficiently employ endoscopic suture ligatures and loop ligatures by using slip knots that have better slippage power and may lock themselves; has not provided ligator devices and slip knots with suture strands sufficiently long to be manipulated extracorporeally to allow tightening and locking the knot itself after it is applied on the target tissues, and allow the ties to be further secured with additional extracorporeal knots as is done in open surgery. The prior art has not provided easy extracorporeal tying techniques for suture ligatures that use slip knots without a "sawing effect" on tissues. Particularly, the prior art has not provided the means to complete intracorporeally the knot of the pretied knot suture forming a noose of small size that can be tied with a negligible amount of sawing effect on the tissues, if any.